FR3075160A1 - PLUNGER EXPIRY PRESSURE CONTROL SYSTEM FOR DIVING VENTILATION EQUIPMENT - Google Patents

Abstract

A diver's expiratory pressure control system for diving equipment having a ventilatory circuit, comprising a one-way valve acting on an expiratory outlet of the ventilatory circuit, and a brake configured to exert an adjustable stress on the one-way valve to control the pressure of the gas issuing from the expiratory outlet so as to generate a positive expiratory pressure in the ventilatory circuit of the equipment and thus prevent or treat pulmonary edema of immersion.

Description

SYSTEM FOR CONTROLLING THE EXPIRATORY PRESSURE OF A DIVER FOR A DIVING VENTILATION EQUIPMENT

The invention relates to diving devices and more particularly to a device for the ventilatory part of diving systems to prevent and participate in the treatment of pulmonary immersion edema.

Immersion pulmonary edema is an increasingly frequent pathology, secondary to cardiac decompensation following the impact of a constraining environment on a diver. In fact, the immersion causes a phenomenon of contention of the soft tissues, that is to say of the lower limbs and of the abdomen, with redistribution of the peripheral blood volumes towards the thorax. The cold, associated with immersion, causes the vessels to close and slows the heart rate. The increase in the amount of oxygen caused by the increase in ambient pressure as the diver descends, worsens the above-mentioned phenomena and decreases the force of contraction of the heart muscle. These respective mechanisms generate an overload of the heart which, when the cardiovascular system is defective or aging, leads to an early leak of blood fluid into the lungs. Congestion in the lungs, also called pulmonary edema, then causes a decrease in blood oxygenation which can quickly lead to discomfort.

A better understanding of this pathology and the recent development of recreational diving are responsible for a marked increase in the number of pulmonary immersion edema. It even becomes the second leading cause of diving accidents, just behind the desaturation accident, and is also the leading cause of death for the diver. Immersion pulmonary edema accounts for around 45% of cardiac arrest while diving. The genesis of pulmonary immersion edemas takes place during the first twenty minutes of the dive and worsens during the ascent with the change of position of the diver and therefore of the ventilatory pressure regimes.

The pathophysiology of immersion pulmonary edema has remained largely unknown for a long time. However, the demonstration of the cardio-circulatory part in pathophysiology (Louge et al., “Pathophysiological and diagnostic implications of cardiac biomarkers and antidiuretic hormone release in distinguishing immersion pulmonary edema from décompression sickness”, Medicine (Baltimore), 95 ( 26): e4060, June 2016), of the rapid aggravation of the symptomatology during the verticalization of the plunger, which leads to a loss of the expiratory counter pressure (Coulange et al., “Pulmonary oedema in healthy SCUBA divers: new physiopathological pathways ", Clin. Physiol. Funct. Imag., 30 (3): 181-186, 2010), as well as similarities with drowning, showed the interest of considering the prevention and treatment of pulmonary edema. immersion through the generation of positive expiratory pressure (Michelet et al. "Acute respiratory failure after drowning: a retrospective multicenter survey", Eur. J. Emerg. Med., 2015). Positive expiratory pressure is the expiratory pressure maintained within the airways. It helps prevent collapse (sagging lung tissue due to pressure from pleural effusion, tumor, or pneumothorax). In addition, by increasing the period of time during which gas exchanges between the alveoli and the capillary occur, it also makes it possible to avoid the formation of atelectasis (retraction of the pulmonary alveoli).

Document US 1984/4436090 presents a device for regulating ventilation comprising a piston which can exert pressure on a valve, the valve used to control the flow of gas when inhaling and exhaling a person for an application. medical (respirator or resuscitator). This device can provide positive expiratory pressure and can also be used for aeronautical ventilation aid applications. Document US 2004/035414 presents a ventilating device for diving equipment, in particular for a snorkel, which can provide a positive expiratory pressure. This device slows the ventilation cycle of the diver, balances the ventilation work between inspiration and expiration and minimizes the risk of development of atelectasis. However, neither of these devices can prevent or treat immersion pulmonary edema.

Other documents (EP 1500586, US 1993/5259374) present adjustable devices for regulating the ventilation of the plunger during inhalation, but they do not generate positive expiratory pressure and therefore do not make it possible to prevent or treat edemas. immersion lungs.

The invention aims to remedy the aforementioned problems of the prior art and more particularly, it aims to provide a device for preventing and treating immersion pulmonary edema by generating variable positive expiratory pressure. According to the invention, this prevention device can generate an adjustable positive expiratory pressure and thus control the diver's expiratory pressure for diving ventilation equipment. It includes a one-way valve acting on the expiratory outlet of the ventilation equipment and a brake configured to exert an adjustable stress on the valve so as to control the pressure of the gas issuing from the expiratory outlet, therefore of the gas exhaled by the plunger. With the invention, the diver can for example benefit from a higher or lower resistance to expiration to prevent the risk of pulmonary edema of immersion during an effort immersed in cold water and at great depth. Conversely, the diver can immediately cancel this resistance to expiration in the event of a panic rise to prevent a risk of chest barotrauma (or pulmonary overpressure) linked to the sudden expansion of the gas contained in the lungs.

An object of the invention is therefore a system for controlling the expiratory pressure of a diver for diving equipment having an expiratory circuit. The system includes a unidirectional valve acting on an expiratory outlet of the ventilatory circuit, and a brake configured to exert an adjustable stress on the unidirectional valve in order to control the pressure of the gas coming from the expiratory outlet, so as to generate a positive pressure in the diving equipment breathing circuit.

According to particular embodiments of the invention:

- The brake can be an adjustable relief valve comprising a hardening spring and a setting screw for adjusting the resistance of the spring;

- The system may include a declutching system enabling the brake to be deactivated, which may consist of a central tubular rod and coaxial with the setting screw;

- The system can include a pressure sensor in the expiratory circuit of the ventilatory circuit;

- The brake can be a solenoid valve;

- The solenoid valve can be controlled electronically following measurements provided by the pressure sensor;

- The brake can include eyelets, shutters or a diaphragm;

- The opening level of the eyelets or shutters or the diaphragm can be controlled electronically following measurements provided by the pressure sensor;

- The system allows to generate at least two discrete levels of positive expiratory pressure;

- The system allows to generate positive expiratory pressure levels among the levels (0; 2.5; 5; 7.5 and 10 mbar).

Another object of the invention is a regulator, the second stage of which comprises a system for controlling the expiratory pressure as claimed in any one of the embodiments of the invention.

Yet another object of the invention is a recycler, the recycler comprising a system for controlling the expiratory pressure as claimed in any one of the embodiments of the invention.

The invention also relates to an autonomous diving suit comprising a system for controlling the expiratory pressure of a diver as claimed in any one of the embodiments of the invention.

Other characteristics, details and advantages of the invention will emerge on reading the description made with reference to the appended figures given by way of example and which represent, respectively:

- Figure 1, an illustration from above of the implementation of an expiration control system on a regulator according to an embodiment of the invention;

- Figure 2, a sectional illustration of the implementation of an expiration control system on a regulator according to an embodiment of the invention;

- Figure 3, an illustration of the implementation of an expiration control system on a recycler according to an embodiment of the invention.

As is generally accepted, diving equipment can include all or part of a set of equipment for diving including a wetsuit, a mask, flippers, ballast, a buoyancy compensator and at least one bottle of dive containing a mixture of respiratory gases, such as nitrox, heliair, hydroxide, trimix, heliox and hydréliox. Most often, the gas mixture is compressed air. Diving equipment within the meaning of the invention includes a regulator or a rebreather allowing the diver to breathe via a mouthpiece.

A regulator is an open circuit diving equipment allowing a diver to breathe the gas contained in his diving tank at the pressure at which he evolves.

A rebreather is closed circuit diving equipment, allowing the gas exhaled by a diver to be recycled, so as to extend the dive time and reduce the weight of the diving tanks.

An autonomous diving suit is generally defined as an individual device allowing its user to breathe and evolve freely underwater with a reserve of compressed breathing gas.

Figure 1 shows a top view of the second stage of a regulator according to an embodiment of the invention. The arrival of a medium pressure gas from the first stage of the regulator to the second stage is ensured by a hose 100. A button 101 makes it possible to adjust the flow of gas arriving in the second stage by the hose 100. This medium pressure gas penetrates in the dry chamber 102 of the second stage of the regulator, and is then relaxed when arriving in the mouthpiece 104. It is the inspiration of the plunger in the mouthpiece 104 which triggers the passage of gas from the dry chamber 102 towards the mouthpiece 104. The inspiration or expiration of the plunger controls, for example, the opening of a valve which allows gas to pass from the dry chamber 102 to the mouthpiece 104 during inspiration or block the gas in the dry chamber 102 on expiration. The pressure of the exhaled gas is adjustable by means of a brake 105 and the exhaled gas is evacuated from the second stage of the regulator by the evacuation whiskers 106.

FIG. 2 shows a section of the second stage 20 of a regulator according to an embodiment of the invention. The arrows symbolize the movement of gas in the second stage of the regulator. In this implementation, the brake 105 comprises a setting screw 200 and a hardening spring 201. The brake 105 makes it possible to act on washers 202 which act on membranes 203. The membranes 203 and the washers 202 thus form a unidirectional valve 204. The plunger can act on the setting screw 200 to adjust the resistance of the hardening spring 201. During the inspiration phase, the gas present in the dry chamber 102 passes into the mouthpiece through the opening of the membranes 203. During the expiration phase, the membranes 203 close, completely or partially depending on the resistance of the hardening spring 201, and the exhaled gas is evacuated by the evacuation whiskers 106. By controlling by the adjusting the resistance of the hardening spring 201 the level of closure of the membranes, to have a complete or partial closure, the plunger can act on the pressure of the exhaled gas.

The clinical manifestations of pulmonary immersion edema often appear during the ascent phase or during the prolongation of the diving session. They therefore do not always appear at the same time according to the divers or with the same intensity. It is therefore important to be able to adjust the positive expiratory pressure at the onset of symptoms, or even anticipate the genesis of edema by a preventive trigger as soon as environmental conditions become restrictive. In the embodiment described, the plunger acts directly on the setting screw 200 according to its feeling.

Furthermore, during the ascent, the verticalization of the plunger causes a large difference in pressure between the regulator which is in the mouth and the lungs of the plunger. It is then necessary to generate a stronger positive expiratory pressure than downhill in order to prevent pulmonary edema from immersion or to treat its symptoms.

The second stage of the regulator may also include a declutching rod 205 which makes it possible to deactivate the brake, that is to say to cancel the resistance of the hardening spring 201. This declutching rod 205 constitutes a safety as regards the level d '' solid obstruction of the system or ascent panic requiring the absence of obstacle on expiration. The declutching rod 205 is central and coaxial with the setting screw 200. The valve 204, the brake 105 and the declutching rod 205 are held in place by means of a fixed housing 206. This fixed housing 206 also includes a safety channel declutching 207.

In an alternative embodiment of the invention, a pressure sensor is placed in the expiratory circuit to measure the pressure of the gas exhaled by the plunger. According to one embodiment, the sensor can be positioned at the level of the mouthpiece 104.

Advantageously, the measurements can be retrieved in order to electronically control the brake 105. An electronic brake control makes it possible to more effectively detect any symptom linked to the appearance of pulmonary edema and to generate any pressure control action more quickly. expiratory. In one embodiment with integrated sensor, the brake 105 is a solenoid valve. The brake can also be made up of eyelets, shutters or be a diaphragm, the eyelets, shutters and diaphragm being outlet orifices having a variable level of opening. More generally, the brake can take any form allowing the level of closure of the outlet surface to be varied.

Thus, the system includes two operating modes: one says passive and the second says active. The passive mode is characterized by the absence of positive expiratory pressure and is the preferred mode for the descent of the diver or may be the mode imposed in the event of an emergency ascent where expiration must be facilitated. The other operating mode, called active mode, is characterized by the generation of a positive expiratory pressure by the implementation of the system of the invention. The active mode is used during the ascent phase of the diver or during an extension of the diving session. The active mode can be operated semi-autonomously by the diver who can adjust the level of the positive expiratory pressure by activating the setting screw, or be operated automatically by being for example controlled by a dive computer worn by the diver. The dive computer records the dive parameters of the diver and thus provides data on the symptoms experienced by the diver in order to activate the expiratory pressure control system. In an alternative embodiment, the diving equipment may include a plurality of sensors making it possible to provide data which can enrich the detection of symptoms indicative of immersion pulmonary edema.

According to another embodiment of the invention, the brake 105 makes it possible to generate at least two discrete levels of positive expiratory pressure. The discrete 0 mbar level belongs to the possible levels of positive expiratory pressure.

To meet known standards, in one embodiment, the brake makes it possible to generate positive expiratory pressure levels from the following levels:

- 0 mbar;

- 2.5 mbar;

- 5 mbar;

- 7.5 mbar; and

- 10 mbar.

Advantageously, the levels of positive expiratory pressure are chosen from the following levels: 2.5 mbar; 5 mbar; 7.5 mbar and 10 mbar.

These values of positive expiratory pressure given by way of nonlimiting example, correspond to the levels likely to prevent the genesis of a pulmonary edema in emergency medicine while not reaching levels likely to create a pulmonary overpressure and to respect pressure regime limits for regulators (see standard NF EN 250, June 2014).

Figure 3 shows the implementation of one of the embodiments of the invention on a diving rebreather. The arrows symbolize the movement of gas in the recycler. When the plunger inspires, the recycler supplies gas to the plunger from the inspiratory lung 300. This gas reaches the mouthpiece 301 by a hose 302. In the mouthpiece 301, the inspired gas passes through a non-return valve. of inspiration 303 before reaching the mouth of the diver. When the plunger expires, the exhaled gas is found in the mouthpiece 301 and passes through the expiration check valve 304. A brake 305 adjustable by the plunger allows to act on the opening of this valve 304. In limiting its opening, the brake 305 can generate a positive expiratory pressure in the mouthpiece 301, making it possible to prevent or treat immersion pulmonary edemas.

After having passed through the expiration check valve 304, the exhaled gas arrives in the expiratory lung 306 by a hose 302. One or more bottles of respiratory gas 307 supply the expiratory lung 306 with respiratory gas (supply symbolized by the reference 308 in Figure 3). The gases then present in the expiratory lung 306 pass through a filter 309. This filter 309 makes it possible to filter the carbon dioxide so that the gases then entering the inspiratory lung 300 no longer contain carbon dioxide.

The invention has been described for several embodiments in order to present the general principle. However, a person skilled in the art can adapt the invention to other embodiments without deviating from the essential characteristics described here. The embodiments described should be considered in all respects only as illustrative and not restrictive.

Claims (13)

claims 1. A diver's expiratory pressure control system for diving equipment with a ventilatory circuit, comprising: - a unidirectional valve acting on an expiratory outlet of the ventilatory circuit; and a brake configured to exert an adjustable stress on the one-way valve in order to control the pressure of the gas coming from the expiratory outlet so as to generate a positive expiratory pressure in said respiratory circuit. 2. A control system for the expiratory pressure of a plunger according to claim 1 wherein said brake is an adjustable relief valve comprising a hardening spring and a setting screw for adjusting the resistance of said spring. 3. A control system for the expiratory pressure of a plunger according to claim 1 or 2 further comprising a declutching system for deactivating said brake. 4. A system for controlling the expiratory pressure of a plunger according to claim 3 wherein the declutching system comprises a central tubular rod and coaxial with said calibration screw. 5. A system for controlling the expiratory pressure of a plunger according to any one of the preceding claims further comprising a pressure sensor in the expiratory circuit of said ventilatory circuit. 6. A control system for the expiratory pressure of a plunger according to claim 5 wherein the brake is a solenoid valve, the solenoid valve being controlled electronically following measurements provided by the pressure sensor. 7. A system for controlling the expiratory pressure of a plunger according to claim 6 wherein the brake comprises eyelets or obturators or a diaphragm. 8. A control system for the expiratory pressure of a plunger according to claim 7 in which the level of opening of the eyelets or obturators or the diaphragm is controlled electronically following measurements provided by the pressure sensor. 9. A system for controlling the expiratory pressure of a diver according to claim 1, in which the brake makes it possible to generate at least two discrete levels of positive expiratory pressure. 10. System for controlling the expiratory pressure of a plunger according to any one of the preceding claims, in which the brake makes it possible to generate positive expiratory pressure levels among the levels (0 mbar; 2.5 mbar; 5 mbar; 7 , 5 mbar and 10 mbar). 11. Regulator for diving comprising at least: a first stage making it possible to relax a high pressure gas so as to obtain a medium pressure gas, and a second stage making it possible to receive said medium pressure gas and to lower the pressure of said medium pressure gas to supply low pressure gas to a ventilable plunger, characterized in that the second stage of the regulator comprises a system according to any one of claims 1 to 10 to control the expiratory pressure of the plunger. 12. Rebreather for diving comprising a system for controlling the expiratory pressure of a diver according to any one of claims 1 to 10. 13. Autonomous diving suit comprising a system for controlling the expiratory pressure of a diver according to any one of claims 1 to 10.